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Ablation model measures hypersonic gas plumes

Project lead: Alex Povitsky, Ph.D., The University of Akron Research title: Modeling of ablation in hypersonic flightFunding sources: Dayton Area Graduate Studies Institute, Air Force Office of Scientific Research & Air Force Research Laboratory

Scientists are developing hypersonic aircraft that can travel at speeds beyond Mach 5 (3,800 mph) and travel from New York to London in less than an hour. In military applications, flight above Mach 8 will be needed for effective homeland security.

Several technical obstacles remain, however. At hypersonic speeds, shock waves created by the compression of air in front of the aircraft increase in strength and number. The aircraft body experiences turbulence, and the air becomes a swarming jumble of hot gases, which transfers heat to the aircraft.

Engineers have addressed the problem by constructing thermal protective shields that slowly burn away — a process called ablation — creating gases that carry heat away from the aircraft and leaving behind a solid material that insulates the craft.

“Extensive research has been conducted that predicts the ablation rates of thermal protective shields due to hypersonic flow,” said Alex Povitsky, Ph.D., an associate professor of mechanical engineering at The University of Akron.

“The interaction of small-scale, but high-intensity, plumes can significantly affect the heat transfer between hypersonic gas and the shield. However, the majority of studies based on heating tests or flight test data don’t take into account the effects of gas plumes.”

Through access to the IBM Cluster 1350 at the Ohio Supercomputer Center, Dr. Povitsky, Dr. Kedar Pathak and graduate assistant Nathan Mullenix are developing a computational methodology for simulating the ablation of carbon shields, complete with local and multiple ablation plumes and subsequent multiple plumes.